HOMICIDE: Detectives are not ruling out the possibility that Prince was murdered

They are hunting for doctors or “handlers” who treated the star with drugs amid claims that the rock legend had an opium addiction.

Police chiefs in Minneapolis have refused to rule out a criminal homicide charge, Prince, who died on Thursday at his Paisley Park estate in the city, could have been killed, according to an unnamed business associate of the music icon.

Detectives have been given “carte blanche” to look into his affairs over the last two years.

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TRIBUTES: Fans have left tributes and flowers at Prince's Paisley park mansion

Staff who work at Paisley Park are having their mobile phones, computers and email accounts examined by the authorities.

The singer was found dead in a lift at his mansion.

A police source said: “A crack team have been assigned with learning minute by minute what Prince was doing during his final days.

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FORTUNE: Prince's sister Tyka is said to dealing with Prince's affairs since his death

“But the investigation will also look into his activities over the last two years.”

“A crack team have been assigned with learning minute by minute what Prince was doing during his final days”

Police

It is claimed that Prince’s staff had built a “wall of steel” around him to stop details of his alleged opiate addiction leaking out.

The Purple Rain star reportedly had a habit of firing his advisors if he did not agree with what they said.

Prince: 1958 - 2016

Musician Prince was found dead aged 57 at his Minnesota estate just days after being rushed to hospital.

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Legendary pop icon Prince died aged 57, April 21, 2016

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MYSTERY: A police team has been assigned to discover exactly what happened on the day he died

Meanwhile, the battle for his £200million fortune has begun with sister Tyka Nelson, a former crack addict, said to be “calling the shots”.

Lawyers are scrambling in a hectic battle over the rights to the star’s mammoth song book. Tyka, 55, has been handling his affairs since his shock death but even bosses at record company Warner Bros are unsure of where his riches will go.